Prostaglandin E.sub.2 (abbreviated as PGE.sub.2) has been known as metabolite in the arachidonate cascade. It has been known that PGE.sub.2 possesses cyto-protective activity, uterine contraction, induce of pain, promotion of digestive peristalsis, awakening effect, suppression of gastric acid secretion or reduction of blood pressure and diuretic activity etc.
In the recent study, it was found that PGE.sub.2 receptor was divided into some subtypes which possess different physical role from each other. At present, four receptor subtypes are known and they are called EP1, EP2, EP3 and EP4 (Negishi M. et al, J. Lipid Mediators Cell Signalling 12, 379-391 (1995)).
PGE.sub.2 possesses a variety of physiological activities, so the undesired action other than the aimed one is shown as side effect. The research for the role of each receptor subtype and the investigation of the compound which only shows the effect on the specific subtype have been carried out to overcome such a problem.
In these subtypes, it has been known that EP1 subtype relates to induce of pain, fever and diuresis (Br. J. Pharmacol. 1994, 112, 735-40; European J. Pharmacol. 152 (1988) 273-279; Gen Pharmacol. September 1992, 23(5) p805-809). Therefore, to antagonize against this receptor is considered to be useful as analgesics, as antipyretic agent and as treating agent for pollakiuria.
The present inventors et. al. have studied to find the compound which can bind to EP1 receptor selectively, have found that the benzenesulfonamide compounds of the formula (I) can bind to EP1 receptor selectively and strongly and scarcely bind to other receptor subtypes, and then have achieved the present invention.